Evidently,
Sorry to hear about your s-i-l. The story sounds rather shocking. If it became public knowledge in your community (a newspaper story, etc.) that the JW's were rejecting a member because she left her husband for fear of violence against her or her baby, and then threatened to reject her parents as well if they didn't throw her out, I think that would bring some very unwelcome attention to the JW's. Perhaps it would cause them to change their position. Maybe there is more to the story, but when I was in, there was a policy that under extreme cases involving violence, a woman had a right to leave her husband. She just couldn't remarry unless he committed "adultery" first.
This is what it says in writing, but in my experience, it's not what happens IRL. A battered wife is encouraged to stay with her abuser first. If she refuses, then she is required to prove adultery on the batterers part if she wants to have a chance to remarry. This is true even in the case when the woman's life is in danger. My jw husband was committed twice by force to mental institutions in two different states. The result was the same in both congregations. It's hard to tell why the s-i-l is being df'd. In my case, I didn't know that there was an option to fade. I was so desperate to get away from this dangerous man that I offered to d'a myself, and the elders, who btw, showed up at my home unannounced and uninvited, said that they would df me instead. And they did. The s-i-l could've been df'd simply for her indignation that the organization insists that she either stay with an unbalanced, abusive husband or hang around to prove his infidelity, regardless of her safety.
If you read the experiences under "Battered Lambs" at silentlambs.org, you will see that the stories are basically all the same. The woman is mentally and/or physically abused, and the elders' answer is for HER to be a better wife and wait on Jehovah. The abusive husband is seldom disciplined. When the situation becomes unbearable or too dangerous for the woman to remain in the marriage, indignation develops, because the requirements of the organization are too stringent and really don't make sense. The VICTIM is made out to be the criminal. People who are at their breaking point or whose lives are in danger will do anything to get away from the abusive situation. Being a battered wife in the organization is very similar to being a molested child. There is no graceful way to protect yourself, keep your sanity and stay in the cult, because the way the rules are set up is that the abuser continues to have domination over the abused, even after they are physically removed from the situation.